The present invention relates to a method and a plant for supervising and controlling field lighting at an airport, and which optionally include presence detectors.
The traditional implementation of a system for field lights is as follows.
High-intensive and low-intensive lightings along approach paths, runways and taxiways are supplied from one or more supply points, so-called cabinets or stations situated in the airport field, usually two for a field with one runway. These supply points are fed with high voltage unregulated electricity which is transformed down to 380/320 V and the supply points contain regulator equipment, thyristor or transducer regulators or regulating transformers for converting the unregulated electricity into controlled, regulated electric power for supplying the light units, which takes place via several power supply loops. Supply takes place in two principally different ways, i.e. by series of parallel feed to the lightings. Each lighting is provided with a transformer for retransformatting the electricity to a suitable low voltage for supplying the lighting with power, in addition, the supply points also contain a supervisory system which monitors the status of the field lighting plant, e.g. such as to ensure that a sufficiently large number of light units function, that the intensity of the light units is correct etc. The supply points, i.e. the cabinets, communicate via a communication link, inter alia with the traffic control tower supervising and operating panel, from which the regulating and supervisory systems are controlled, and at which information from the systems is received. This communication takes place via separate wire pairs for each function, or with time multiplex transmission on wires or optical fibres.
The object of the present invention is to present a new method for supervising and controlling field lighting, and to provide a new field lighting plant, where each individual lighting is addressable and includes a communicating local regulator and a monitoring unit for supplying power to, and monitoring the lighting. Thus each lighting or subsystem of lightings can be controlled individually, irrespective of the sections into which the power cabling is divided.
Furthermore, the invention enables a presence indication system for detecting vehicle and aircraft movements on the ground to be integrated in the field lighting system implemented in accordance with the present invention.
Communication between the traffic control tower supervision and operating panel takes place via a central computer to a so-called concentrator and loop computer. The communication signals can be in the form of time multiplexed electrical or optical signals on signal cables or optical fibre cables.
A plurality of advantages are achieved by the present invention compared with the already known state of the airport lighting art.
In the implementation of a traditional field lighting system, the different power supply loops are fed via a regulator centrally connected to each loop for regulating the intensity of the lightings connected to the loop. For reasons of safety, the different lighting configurations such as approach lighting, runway edge lighting, glidepath beacons, threshold lighting and taxiway lighting must be fed by several loops in case there should be a regulator or cable fault. A large number of centrally placed regulators are therefore required for controlling the field lighting system, and these occupy large spaces which must often be specially built. With the present invention, on the other hand, each lighting is provided with a local regulator which is placed at the light fitting or in a so-called fitting well associated therewith. At the supply point there will only be a so-called concentrator, sling computer, contactor and modem. This results in less voluminous equipment, which gives savings in space and cost compared with the implementation carried out in a conventional way. In addition, the necessary redundance is obtained automatically with the method of implementation in accordance with the invention.
With a conventional method of implementation there is further required one or more lamp transformers at each lighting. These are heavy and take up considerable space. With the present invention, one or more of these transformers can be replaced by a small and light electronic unit on the fitting for intensity regulation and monitoring each individual lighting.
Since, in accordance with the present invention, each lighting can communicate and is addressable with the aid of its electronic unit, and is thus provided with local intelligence, a lighting with several individual illumination points can control these separately in spite of the supply taking place merely over a single phase or a common cable. The necessary amount of power cable can thus be substantially reduced.
Field lighting plant for airports in accordance with the invention can advantageously be made up of certain modules, namely the lighting electronic unit (hereinafter denoted the AE unit), loop computer, concentrator and modem, where the concentrator and loop computer are realized with the same hardware but with different software, the plant being completed by a central computer and a supervising and operating unit in the traffic control tower (hereinafter denoted TWR). This simple, modular implementation method reduces the hardware costs for a given field lighting plant as well as design costs for a given lighting configuration. Since an ordinary-sized airport has several hundred lightings, the size of the AE unit manufacturing series will be considerable, which considerably reduces the manufacturing cost of each AE unit.
The modular method of implementation means that service and maintenance are facilitated. If an individual lighting does not light, this can either be due to the lamp or the corresponding AE unit failing, or both. In the great majority of cases, it is the lamp that fails, and therefore it is changed first. If a section coupled to a loop computer does not light, this can only be due to failing of the loop computer and modem, and this unit is then changed. Service and maintenance work will thus be extremely simplified, which is an advantage from the time, cost and personnel expects.
With conventionally implemented field lighting systems, there must be an ocular inspection of the field lighting at least once a day to determine which light units are defect. For airports with heavy traffic this must take place at night, since the runway system is not available for inspection during daytime. This results in increased costs. With the present invention this inspection is eliminated, since each lighting is individually monitored and a presentation of the status of each one can be obtained via the sling computer, concentrator and central computer, either on a display or printed out on a printer. In addition, monitoring can take place without the field lighting being lit up, since the AE unit only needs to drive a minimum amount of current through the lamp in order to decide whether it is failing or not. This method saves energy. Each AE unit can furthermore be implemented to enable measuring of the operating time of the light source to which it is connected. Since the average light (illumination time) of the lamps in question is well known, this individual information as to lamp status, namely illumination time and functioning/failing enables planned maintenance of the field lighting plant, which gives better status of the plant and more effective utilization of maintenance personnel. The total illumination time of each light source is suitably continuously registered at e.g. the central computer.
According to an advantageous embodiment of the plant in accordance with the invention, each lighting includes two separate light sources, the lighting configurations of which are identical. Only one light source is in service at a time, but should it fail the other light source is automatically connected, and information is sent that there is no reserve lamp for the lighting.
Since each lighting is addressable in accordance with the present invention, there is the possibility of guiding aircraft, using parts of the field lighting system, for taxiing to and from runways, i.e., to arrange a so-called taxiway guidance system. This can be arranged by the lighting system along the central line of a taxiway being sectioned so that a given section is given a group address. This section can then either have its own operating button in a control tower panel where the section is lit when the appropriate button is pressed, or the central computer in the system can select a path with given input values for the taxiing path of the aircraft, taking into consideration any maintenance work on the taxiway, or to other aircraft movements etc. The decided path can either be lit up simultaneously in its entirety or successively in front of the aircraft. In existing plants this sectioning has been achieved by each section being provided with a separate power supply. With the present invention, the section is performed, with the aid of the AE units"" addresses, in the software, which drastically reduces the installation costs for a guidance system, and simplifies any future changes in the section configuration.
The invention can also be used for detecting vehicle and aircraft movements on the ground, i.e. it can form a so-called ground traffic detection system. In airports with heavy traffic, the collision risk between aircraft/aircraft and aircraft/vehicle is namely a great problem in poor visibility conditions. Since the inventive lighting system includes xe2x80x9cintelligentxe2x80x9d and addressable AE units at each point where there is a lighting, every taxiway and runway can be divided into frequent identification blocks. This inventive implementation of the plan, supplemented with a presence detector allocated to each fitting the complete field lighting system or parts thereof enables detection and supervision of aircraft and vehicle movements along the rolling way system or parts thereof. The signals from the ground traffic detectors are taken up by the AE units and transmitted together with other lighting information via loop computer and concentrator to the central computer, which depicts the ground traffic on a display. The central computer, or a special supervisory computer, can give an alarm for situations where unpermitted ground traffic situations occur. This ground traffic detection system integrated with the field lighting system is very cost-effective compared with existing ground radar systems. The present invention moreover permits that only those parts of the rolling way system selectively chosen from the safety aspect are provided with ground traffic detection capacity, whereby further cost savings can be made.
In accordance with a further advantageous development of the invention, the guidance system is integrated with the ground traffic detection system such that the center line lights included in the guidance system are lit up or extinguished or change lighting color, thereby switching between operating parameters, in front of and after the taxiing aircraft, respectively, lighting up and extinguishing the center line lights taking place individually or in sections with the aid of control signals from the presence detection of the aircraft.
According to another embodiment of.the plant, each lighting position where an AE unit is to be connected is provided with an unique address, which is automatically transferred to the AE unit when the unit is connected, such that this address is tied to its location and is not lost if an AE unit were to be changed.
An advantageous method of realizing an address which is not tied to the AE unit but to its position is to arrange a plurality of permanent magnets in the AE unit mounting such that these magnets have a unique combination of north and south pole orientation, giving the position in question an unique address which is automatically transferred to the AE unit by magnetic field-sensitive elements when the unit is connected. An eight bit address can be realized using eight magnets, for example.
According to a still further advantageous embodiment of the plant, and via the AE unit, the lightings are made for three-phase supply enabling the supply to be dimensioned to cope with a phase failure up to a predetermined current or voltage level. Up to this level all lightings light with no change if there is a phase failure. The central computer can be programmed such as to increase the number of lightings which are extinguished with an increasing modulation in order that the maximum transmitted power for two phases is not exceeded.